This invention relates to a method of, and apparatus for, treating seeds with a chemical just prior to planting. More particularly, it relates to an in-the-field treating system in which untreated seeds are sprayed with a moist chemical as the seed is being transferred from a grain hopper to a furrow by a seed planter of the "plateless" type, such as those commonly used for planting corn, wheat, sorghum, and other field-grown grains or vegetable crops.